Simulation of Climate Change Effects on Evapotranspiration, Photosynthesis, Crop Growth, and Yield Processes in Crop Models

Climate change is a challenge for global food security. Crop models are indispensable tools to assess the impact of changing climatic boundary conditions on food production. However, comparisons among international models have revealed significant uncertainty; there is a wide range of model results, likely due to large variation in the description and parametrization of important processes in each model. In this chapter, we provide an overview of process approaches used within crop models that help with impact assessments, and which are relevant to specific responses to climate change. This effort focuses on evapotranspiration, crop growth and development, and crop responses to water availability and elevated CO 2 . For process comparisons, we use the model approaches and parametrization for wheat, which is one of the best investigated and most frequently simulated crops. We also look at processes that are currently not well represented in crop models due to the lack of suitable data.